The terror of an approaching enemy brings a sudden and absolute paralysis to the Babylonian leadership. This overwhelming fear is most evident in the reaction of the king of Babylon, identified as Belshazzar [רד״ק]. Upon receiving reports detailing the sheer might and bravery of the attackers, a profound panic falls over the king.
The commentators agree that this terrifying news drains the ruler of all his physical strength. His hands become entirely weak and limp, leaving him completely unable to mount a defense or fight back. This distress is not just a passing fear, but a tangible force that tightly grips and traps him. He is overcome by a severe, violent trembling, a shuddering panic that strikes him with the sudden and intense agony of a woman in labor.